1. Field of the Invention
The invention relates to a holding device for fixing a protective cage to the shaft of an outboard motor of a boat. The invention also relates to a protective cage for an outboard motor utilizing the holding device. The invention further relates to a method of protecting the propeller of an outboard motor as well as a method of attaching a protective cage to an outboard motor using the holding device.
2. Description of the Prior Art
Such a protective cage is usually attached to the shaft of the outboard motor. On the one hand this attachment must be stable, so that the protective cage, as far as possible, withstands a knock e.g., against a rock under water. On the other hand, the attaching much be carried out in a simple manner, so that when required, e.g., for cleaning and maintenance work on the propeller, the protective cage can be quickly removed from and reattached to the shaft of the outboard motor without special tools. Furthermore, it should be possible to easily fix the protective cage holding device to the shafts of different outboard motors available on the market or already in use.
Protective cages for outboard motors of boats are known (see, for example, DE 199 03 998 A1). They are used to protect people and animals from injury by the rotating propeller, as well as, to protect the propeller from knocking against hard objects, such as rocks that are difficult to see under water.
In U.S. Pat. No. 3,035,538 there is described a protective cage for an outboard motor of a boat. The protective cage and the related ring for fixing the cage on the boat motor are made in a single piece. Therefore, an economic manufacture requires that the protective cage be made of plastic, for example, by injection molding. However, such a plastic material has the disadvantage that in the long run it is neither corrosion resistant against salty sea water nor resistant to aging under strong sunlight exposure. This may lead to the fact that the corroded and/or aged plastic material shatters by an impact, which causes additionally a risk of injury. Besides this, the single-piece nature of the known protective cage makes its adapting to different forms of motors more difficult and increases the costs for a replacement of a cage deformed by an impact.
U.S. Pat. No. 3,075,491 also describes a protective cage for an outboard motor. The protective cage and the ring for fixing the cage at the motor are designed as a single piece, for example, by a welded joint.
DE 3727322 A1 describes an outboard aggregate for watercrafts, wherein the propeller for its protection is freely rotatable within a cage. The cage is provided with a collar for fixing it to the motor shaft. The single-piece nature if the cage and the collar leads to the above-mentioned disadvantageous.